Some experts, however, say the practice is fine.
"It is safe to cook a frozen chicken in a slow cooker," Quin Patton, a food scientist formerly with PepsiCo, told TODAY. "You just need to make sure the internal temperature gets up to 165 degrees at some point during the cooking process."
Although the slow cooker is capable of reaching this temperature, the USDA says it’s more about timing than temperature and how long the chicken spends thawing in the danger “zone” (between 40 degrees and 140 degrees where bacteria grow most rapidly).
To stay on the safe side of food poisoning, place your chicken in the fridge the thaw out overnight before cooking.
Additionally, where you set up your slow cooker in the kitchen matters. For safer cooking, place the cooker on your stove top.
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